1. Field of the Invention
The present invention relates to films of soft magnetic Fe based alloy containing nitrogen for use as materials of a magnetic head core for e.g. a VCR or a hard disk system.
2. Description of the Prior Art
It is known that typical soft magnetic alloys for use with e.g. a magnetic head include cobalt amorphous alloy and Fe-Al-Si alloy. As higher density in the magnetic recording has been much required, such a soft magnetic alloy for use as a material of a core is now intended to provide higher magnetic saturation.
It is also desired to form magnetic gaps with e.g. bonding glass for enhancing the operational reliability of the magnetic head of a VCR or hard disk. The bonding glass exhibiting a greater bonding strength is high in the melting point and thus, the soft magnetic alloy film should have a better soft magnetic property and higher saturation magnetization after the heat treatment at a high temperature. For example, for producing a soft magnetic alloy film having higher saturation magnetization from a Co based amorphous alloy, it is required to decrease the content of a glass forming element in the alloy. However, the temperature for crystallization in the amorphous alloy film is also decreased, whereby the soft magnetic property after annealing will be declined. In view of thermal stability of the soft magnetic property, the practical saturation magnetization in a soft magnetic alloy film for a magnetic head in e.g. a VCR is about 10 k Gauss at the maximum when a Co based amorphous alloy or Fe-Al-Si alloy is employed.
As understood, for ensuring the thermal stability in the soft magnetic property, the practical saturation magnetization in the soft magnetic alloy film for e.g a VCR magnetic head is about 10 k Gauss at the maximum. However, an improved soft magnetic alloy film having higher saturation magnetization is now required for use with a high density recording head.
The compositionally modulated nitride alloy films developed by us (for example, disclosed in U.S. patent Ser. No. 4836865) are known, in which the nitrogen composition is modulated in the direction of film thickness, as appropriate materials for magnetic heads which can exhibit higher saturation magnetization and has a better soft magnetic property developed after annealing. Such a compositionally modulated nitride alloy film exhibits higher saturation magnetization with mainly Fe based alloy than with Co based alloy and also, less costly. It is therefore advantageous to produce the soft magnetic film with a compositionally modulated Fe based nitride alloy for having a better soft magnetic property and exhibiting improved thermal stability. Accordingly, the compositionally modulated Fe based nitride alloy film should be described in more details of the compositional arrangement or general formula and simultaneously, proved to provide lower magnetostrictive effects.
It is a primary object of the present invention to provide a soft magnetic alloy film for use with a magnetic head, which has a better soft magnetic property developed after annealing and exhibiting higher saturation magnetization, with the use of Fe based alloy, not conventional nitride films, having a compositional modulation of nitrogen. It is another object of the present invention to provide a soft magnetic alloy film for use with a magnetic head, which has a better soft magnetic property ensuring lower magnetostriction and also, can exhibit lower magnetostriction after annealing, with the use of compositionally modulated Fe based nitride alloy films.